In a 5-4 ruling the U.S. Supreme Courtstruck down an important part of the Voting Rights Act of 1965 Tuesday (June 25). The decision nixed a key clause keeping federal supervision of Jim Crow-era voter discrimination tactics in place.

President Obama said he was “deeply disappointed” by the ruling in a statement released later in the day. “I am deeply disappointed with the Supreme Court’s decision today,” he said. “Today’s decision invalidating one of its core provisions upsets decades of well-established practices that help make sure voting is fair, especially in places where voting discrimination has been historically prevalent.”

The Supreme Court on Tuesday effectively struck down the heart of the Voting Rights Act of 1965 by a 5-to-4 vote, ruling that Congress had not provided adequate justification for subjecting nine states, mostly in the South, to federal oversight.

“In 1965, the states could be divided into two groups: those with a recent history of voting tests and low voter registration and turnout, and those without those characteristics,” Chief Justice John G. Roberts Jr. wrote for the majority. “Congress based its coverage formula on that distinction. Today the nation is no longer divided along those lines, yet the Voting Rights Act continues to treat it as if it were.”

The court divided along ideological lines, and the two sides drew sharply different lessons from the history of the civil rights movement and gave very different accounts of whether racial minorities continue to face discrimination in voting.

President Obama, whose election as the nation’s first black president was cited by critics of the law as evidence that it was no longer needed.

The president has called for Congress to “pass legislation to ensure every American has equal access to the polls.”

Acts of voter discrimination are mostly found in Southern states. While national laws blocking prejudice remain, today’s decision makes it easier for lawmakers to change voting rules without waiting for approval from the Justice Department.